1. Field of the Invention
The present invention relates generally to musical stringed instruments and particularly to a string lock assembly for selectively locking and maintaining the strings of a musical instrument against slippage during instrument utilization.
2. Description of the Background Art
Many guitarists and bassists utilize adjustable bridge assemblies or tremolo devices with their instruments to provide for varying string tension and oscillatory motion which allows a note being played to be decreased or increased in pitch or for achieving some other tremolo affect. One problem known with the use of these assemblies and devices is that the strings do not always return to their proper pitch with release of the vibrato arm with the ultimate affect of the instrument coming out of tune.
To overcome the problem of the instrument coming out of tune when utilizing an adjustable bridge assembly or tremolo device, several devices have been developed that are intended to utilize a mechanism designed to lock in place the strings of musical instruments after the strings have been initially tuned.
U.S. Pat. No. 4,171,661 granted to Rose on Oct. 23, 1979 entitled "Guitar Tremolo Method And Apparatus" discloses an anchoring device that locks the strings in place with the use of a threaded clamping device. With the Rose device the conventional fretboard nut is replaced by a special locking nut assembly with a series of blocks held by single bolts or screws for clamping the strings of a guitar at the end of the guitar's neck. Several disadvantages are readily apparent with the Rose device. For example, in order to re-tune a guitar with the Rose device, it is necessary to use a separate wrench or screwdriver to loosen the blocks and allow adjustment of the strings in tension. Such a time consuming and tedious operation is particularly inconvenient during a live performance, rehearsal, lesson, etc. Furthermore, as stated above, the Rose device requires replacement of the conventional fretboard nut.
U.S. Pat. No. 4,475,432 granted to Stroh on Oct. 9, 1984 entitled "String-Clamping Means" discloses a series of blocks that are clamped together and anchor the strings mounted between the blocks. A threaded bolt serves to tighten the blocks for anchoring and releasing tension on the strings.
U.S. Pat. Nos. 4,574,678 and 4,579,033 granted on March 11 and Apr. 1, 1986, respectively, to Edwards and respectively entitled "String Locking Assembly For A Musical Instrument" and "Locking Nut Assembly For A Guitar", respectively disclose a locking nut assembly to be used behind the guitar's original fretboard nut and in place of the guitar's original fretboard nut. Both devices include a base-plate that is mounted directly to the guitar. The base-plate includes an outwardly disposed surface for supporting the guitar strings and outwardly extending posts at spaced intervals. The posts separate the individual strings. The Edwards devices also include cam action locking devices which serve to lock the strings in place after they have been tuned. In both of the structures disclosed in these patents, the lever tabs are very small and hence, are cumbersome to operate, making the ability to manually apply sufficient torque by manipulation of the fingers difficult. Furthermore, because the lever tabs are nearly flush with the fretboard and may be fulcrumed in the direction of the first fret, this structure interferes with fretting the fingerboard in this location and hence, obstructs the musician's ability to play the instrument. Moreover, the tabs have the propensity of colliding with each other. To avoid this collision the adjacent tabs must be pivoted in opposite directions. In the event immediate pivoting of the tabs cannot be accommodated, the tab is left in an erect position or torqued until it can be pivoted for clearance at a later time. A possible result of this circumstance is that the threads of the locking screws may become stripped.
U.S. Pat. No. 4,667,561 granted to Storey et al discloses a string lock device that includes a plurality of adjustable cam-shaped lever and wedge combinations that lock and release the strings of a guitar. By manually rotating the levers to an overcenter position, the wedges are displaced longitudinally which, in turn, displace the clamping screws and block assemblies for clamping the strings between the clamping blocks and the string lock base. In this procedure when the levers are rotated and the wedges are horizontally displaced forward, there is a tendency for the levers to react in an opposite direction. The torque of these levers transfers a force upon an axial pin or journal that accommodates the stress of the levers when in the locking position. This force is sufficient enough to cause failure to the clamping block.
All of the above-described devices are relatively cumbersome to operate or tend to fail and/or have the propensity of interfering with the playing of the stringed instrument. Furthermore, in designs where the locking clamp has been made integral with the fretboard nut, the ability of filing the fretboard nut to achieve the desired clearance between the strings and the first fret of the guitar or stringed instrument may be interfered. Additionally, in certain instruments that include an adjustable truss rod assembly running within the length of the neck for controlling the curvature of the neck, the previous locking mechanism often obstructs this truss adjustment mechanism.
Because the nut of the instrument must be designed for specific spacing between the strings and the string lock requires a set arc of the strings across the width of the fingerboard, the use of previous integral locking devices required different string locks of different designs for different guitar necks and fingerboards.
Thus, some of the problems with previous devices include, but are not limited to, that the locking nut has a tendency of loosening, breakage thereto is relatively frequent, and/or that the device(s) is(are) not convenient to adjust. In certain previous locking devices a separate tool is required to make the adjustment. Not only is the fact that the tool may not be available for one reason or another, manipulating the tool by one's fingers may not enable the user to provide sufficient torque to assure that the clamping force will satisfy the locking requirements.
While previous locking devices may operate satisfactory under some circumstances, they are all rather unwieldy to operate, and usually require a separate tool for providing clamping force. Moreover, previous string locks which comprise the nut of the instrument, usually are required to be designed for specific spacing between the strings, thus, dictating to the user the spacing of the strings. Additionally, previous nut mounted string locks require a set arc of the strings across the width of the fingerboard, requiring different designed devices for different guitar necks and fingerboards.
Thus, what is needed in the art is an adjustable string clamping mechanism which is quickly and easily manually operated to securely anchor the strings of a musical instrument, without any modifications to the instrument. It is therefore, to the effective resolution of the aforementioned problems and shortcomings that the present invention is directed.